Delta’s program, which kicked off at D.C.’s Reagan National Airport, is in partnership with Clear, a company that already lets customers skip to the front of security lines without identification. To be eligible for the program, one must be a member of Delta’s frequent flyer SkyMiles program and a Clear subscriber.

The first phase of Delta’s program will allow its elite-tier passengers to use their fingerprints, rather than their boarding passes, to enter member lounges. A planned second phase would allow Delta frequent flyers to use their fingerprint in lieu of a boarding pass. Per its privacy policy, which will cover the Delta program, Clear keeps users’ biometric information for the term of their subscriptions. Users can ask for their information to be removed from the company’s servers and close their accounts at any time.

JetBlue’s program works in concert with two entities: the U.S. Customs and Border Protection (CBP) and a tech firm called SITA. Flyers at Boston’s Logan International Airport and Aruba’s Queen Beatrix International Airport will have the option of going into the normal boarding line, or one with a camera that will snap their picture. SITA will send that photo to the CBP, to match it against the agency’s database of passport and visa photos. The match process is instant, JetBlue said.

Neither JetBlue nor SITA has access to the photo database, and the airline will not store users’ biometric information, JetBlue confirmed in an email.

If the facial scan fails to work, passengers will be moved to the traditional line — so don’t travel without your ID just yet.

Neither company has released details on how the government may use information on when and where people’s faces have been scanned, he said, nor are there laws to prevent the government from using these types of programs as part of larger surveillance plans.

“It’s a technology that can easily be used for mass, indiscriminate surveillance,” he said, of facial recognition technology. “Any use for facial recognition for something like this — where it’s the government or companies running a facial recognition search on people — needs to be scrutinized very closely by the public, because of the serious risk of mission creep.”

U.S. Customs and Border Protection did not immediately respond to a request for comment.